UniqueId.suggest: remove unnecessary memory allocation.

If there was N suggestions, we'd allocate N strings unnecessarily.
When trying to check whether a UID is already in the cache, we can
check either the forward mapping (name -> ID) or the backward mapping
(ID -> name), but the former doesn't require any memory allocation so
do that instead (the latter requires converting a byte[] to a String).

Change-Id: I11b1e30e6c8f4f5cfadd2068216610311a950393
Reviewed-by: Berk D. Demir <bdd@mindcast.org>

src/uid/UniqueId.java

@@ -392,14 +392,14 @@ public List<String> suggest(final String search) throws HBaseException {
  final byte[] key = row.get(0).key();
  final String name = fromBytes(key);
  final byte[] id = row.get(0).value();
- final String cached_name = idCache.get(new String(id));
- if (cached_name == null) {
+ final byte[] cached_id = nameCache.get(name);
+ if (cached_id == null) {
  addIdToCache(name, id);
  addNameToCache(id, name);
- } else if (!cached_name.equals(name)) {
+ } else if (!Arrays.equals(id, cached_id)) {
  throw new IllegalStateException("WTF? For kind=" + kind()
- + " id=" + Arrays.toString(id) + " I already have name="
- + cached_name + " in cache, but I just scanned name=" + name);
+ + " name=" + name + ", we have id=" + Arrays.toString(cached_id)
+ + " in cache, but just scanned id=" + Arrays.toString(id));
  }
  suggestions.add(name);
  if ((short) suggestions.size() > MAX_SUGGESTIONS) {